Kerf spreader for mechanical chain saws



July 3, 1962 c. FlLlON ETAL 3,042,088

KERF SPREADER FOR MECHANICAL CHAIN SAWS Filed Jan. 3, 1961 IN VENTORS Camille F/LION Robert BEAU/E6490 PATENT AGENT United States Patent 3,042,688 KERF SPREADER FOR MECHANICAL CHAIN SAWS Camille Filion and Robert Beauregard, both of Weedon, Wolfe County, Quebec, Canada Filed Jan. 3, 1961, Ser. No. 80,372 3 Claims. (Cl. 14332) The present invention relates to mechanical chain saws, and more particularly to an attachment for such saws having the function of a kerf spreader.

It is known that when sawing a tree, a log or the like, the guiding blade and saw chain frequently become jammed or blocked in the kerf or saw cut due to the sides of the kerf closing in on the blade especially at the end of the sawing operation when the tree or log is weakened at the saw cut.

It is consequently the general object of the present invention to provide a kerf spreader for use in combination with a mechanical chain saw in order to prevent the above noted disadvantage.

A more specific object of the present invention resides in a kerf spreader designed to be mounted on the chain saw proper in order to automatically engage the kerf and prevent the same from closing in during the entire sawing operation.

Another object of the invention resides in the provision of a kerf spreader of the characted described which need not be manipulated by the operator of the chain saw and which will yet automatically engage the saw cut and remain in active position independently of the diameter of the tree, log or board being cut, and for the entire sawing operation.

Another object of the invention resides in a kerf spreader as a mechanical chain saw attachment which is of simple and inexpensive construction and yet very efiicient. The foregoing and other important objects of the present invention will become more apparent during the following disclosure and by referring to the drawings, in which:

FIGURE 1 is a perspective View of a tree log and of a mechanical chain saw in sawing position, and also showing the kerf spreader attachment of the invention in operative position;

FIGURE 2 is a side elevation of the chain saw and kerf spreader;

FIGURE 3 is a side elevation of the kerf spreader;

FIGURE 4 is a cross-section along line 44 of FIG- URE 3;

FIGURE 5 is a cross-section along line 5-5 of FIG- URE 3; and

FIGURE 6 is a cross-section along line 66 of FIG- URE 3.

Referring now more particularly to the drawing in which like reference characters indicate like elements throughout, reference numeral 1 indicates the housing of the internal combustion engine of a mechanical chain saw and supplied with fuel from a reservoir 2 and driving the chain saw 3 slidably mounted at the periphery of and guided by the blade 4 which is secured to the housing 1 and projects forwardly of the same in a vertical plane. The housing 1 is provided with the usual handles 5 and 6. The kerf spreader of the invention is generally indicated at A and comprises a bracket 7 rigidly secured to the housing 1 just above the blade 4 and in a common plane therewith. A telescopic arm 8 is pivotally connected at 9 on bracket 7 for pivotal movement in a plane common to the plane of blade 4. The telescopic arm 8 consists of a sleeve like element 10 in the form of a channel member having inwardly turned lips 11 to guide a bar 12 in slidable engagement with the sleeve 10. The bar 12 is retained in retracted position by means of a tension spring 13 secured at 14 to bar 12 and at 15 to the pin constituting the pivot 9 of the telescopic arm to bracket 7. The bracket 7 has a forward extension 16 with a right angular flange 1'7 defining a shelf like element on which abuts the sleeve 10 under action of a spring 18 attached to approximately the middle of sleeve 10? at 19 to housing 1 of the chain saw below the bracket 7 as shown at 26). Thus, spring 18 resiliently maintains the telescopic arm 8 in a position abutting against flange 17 in which the arm 8 is substantially parallel to the long axis of the saw blade 4. A freely rotatable kerf spreading disc 21 is rotatably mounted on a pin 22 secured to the outer end of bar 12. Disc 21 has a triangular cross section forming a thin peripheral edge 23 with diverging side surfaces 24. The disc 21 is disposed in the plane of the saw blade 4 and approximately opposite the center of the blade in the rest position of the device. The device of the invention is used as follows:

The mechanical chain saw is held by handles 5 and 6 in usual manner and is operated to saw a log L or tree trunk, or board, or the like in conventional manner. When the blade 4 has cut down through the log L an amount greater than the width of the saw blade, the disc 21 automatically comes into engagement with the saw cut or kerf at the top thereof. If desired slight pressure may be applied on the disc 21 to firmly engage the kerf. The sawing operation is continued during which time the saw blade moves down through the log L. However, the kerf is maintained to its original width due to the presence of disc 1 which prevents closing in of the kerf. As the saw moves down through the log, the arm 8 extends automatically against the action of spring 13 and also the arm 3 pivots upwardly against action of spring 18, so that the disc 21 remains in stationary position while the saw itself moves down through the log. Once the log is completely cut, the kerf spreader returns automatically to its original position, as shown in FIGURE 2, in full line. It is to be noted that the kerf spreader of the invention does not interfere in any way with the normal handling of the chain saw and the normal sawing operation, and that the blade can be moved transversely of the log, if so desired.

While a preferred embodiment in accordance with the invention has been illustrated and described, it is understood that various modifications may be resorted to without departing from the spirit and scope of the appended claims.

What I claim is:

1. In combination with a portable mechanical chain saw having a housing and a saw chain guiding blade protruding from said housing, a kerf spreader comprising a bracket secured to said housing, a telescopic arm made of telescopically engaged elements which are freely and slidably movable with respect to each other, the innermos-t element freely pivotally attached at one end to said bracket for pivotal movement of said arm in the general plane containing said blade, a wedge-like kerf engaging element pivotally mounted at the outer end of the outermost element of said telescopic arm for firm, stationary engagement with the kerf made by the chain saw, spring means urging said elements of said telescopic arm into retracted position, additional spring means urging pivotal movement of said telescopic arm into a pivoted limit position along one longitudinal edge of said blade, whereby said kerf engaging element remains stationary irrespective of the movements of said chain saw during sawing, said last named movements causing pivotal movement of said arm and slidable movement of the elements of said arm.

2. The combination as claimed in claim 1, further including abutment means on said bracket engageable With said telescopic arm in the limit position thereof.

3. In combination with a portable mechanical chain saw having a housing, an elongated blade protruding from said housing, and a chain saW guided by and slidable along the periphery of said blade, at kerf spreader comprising a bracket secured to said housing adjacent and above said saw blade, a telescopic ann made of telescopically engaged elements which are freely and slidably movable with respect to each other, the innermost element freely pivotally connected to said bracket for pivotal movement of said arm in the plane of said blade and above the same, a first tension spring interconnecting said elements for resiliently urging said telescopic arm into retracted position, a kerf engaging element of tapered cross-section pivotally mounted at the outer end of the outermost element of said telescopic arm, a second tension spring attached to said arm and to said housing be low said bracket for resiliently pivoting said arm into a limit position in Which it is substantially parfllel with the longitudinal axis of said blade, and abutment means on said bracket engageable with said arm for maintaining the same in said limit position against the action of said second spring.

References Cited in the file of this patent UNITED STATES PATENTS 361,218 Foster et al. Apr. 12, 1887 1,125,637 Beaudry Jan. 19, 1915 1,602,040 Neal Oct. 5, 1926 2,698,997 King et a1 Jan. 11, 1955 FOREIGN PATENTS 20,183 Great Britain Sept. 19, 1903 

